Patent application title: Activation-Device Launcher For A Cementing Head

Abstract:

The present invention relates in general to equipment for servicing
subterranean wells and in particular to a cementing head that is intended
to drop a combination of darts, balls, bombs and canisters in order to
activate downhole equipment, launch cementing plugs, deliver chemical
products, or the like.

Claims:

1. A multiple activation-device launching system for a cementing head, the
launcher body comprising a plug-valve through which a process fluid and
activation devices may pass, and through which balls may be launched when
the plug valve is in either the main-flow or bypass-flow position.

3. The system of claim 1, wherein the activation-devices comprise one or
more members of the list comprising: darts, balls, canisters and bombs.

4. The system of claim 1, wherein the activation-devices contain a
chemical substance that may be released after launching of the activation
device

5. The system of claim 1, wherein the valve is a hollow shell.

6. The system of claim 1, wherein one or more balls may be injected and
launched through the plug-valve.

7. The system of claim 1, wherein the plug-valve has a swept cutout
through at least 90 degrees of the valve's range of motion.

8. A method for deploying one or more activation devices into a
process-fluid stream, utilizing an multiple-activation device launching
system for a cementing head, the launching system comprising a plug valve
through which activation devices may pass, and through which balls may be
launched when the plug-valve is in either the main-flow or bypass-flow
position.

9. The method of claim 8, comprising the following steps:i. pumping
process fluid through the main-flow portion of the launching system;ii.
placing the plug-valve in the bypassflow position and, if desired,
allowing at least one ball to pass and enter the process-fluid
stream;iii. placing the plug valve in the main-flow position and, if
desired, allowing at least one dart or other activation device to
pass;iv. if desired, inserting at least one ball into the valve axle,
allowing one or more balls to clear the passageway and enter the
process-fluid stream;v. placing the plug valve in the main-flow position,
restoring process-fluid flow through the main-flow portion of the
launcher body and, if desired, allowing one or more activation devices to
pass; andvi. repeating steps ii. through v. until a sufficient number of
activation devices have been deployed to complete the treatment.

10. The method of claim 8, comprising the following steps:i. pumping
process fluid through the main-flow portion of the launching system;ii.
placing the plug valve in the bypass-flow position and, if desired,
allowing at least one ball containing a chemical substance to pass and
enter the process-fluid stream;iii. releasing the chemical substance into
the process fluid if at least one ball contains a chemical substance;iv.
placing the plug valve in the main-flow position, allowing at least one
dart or other activation device containing a chemical substance to
pass;v. releasing the chemical substance into the process fluid if at
least one activation device contains a chemical substance;vi. if desired,
inserting at least one ball containing a chemical substance through the
valve axle into the process fluid;vii. releasing the chemical substance
into the process fluid if at least one ball contains a chemical
substance;viii. placing the plug valve in the main-flow position,
restoring process-fluid flow through the main-flow portion of the
launcher body and, if desired, allowing at least one activation device
containing a chemical substance to pass;ix. releasing the chemical
substance if at least one activation device contains a chemical
substance.x. repeating steps ii. through ix. until a sufficient number of
activation devices have been deployed to complete the treatment.

12. The method of claim 8, wherein the activation-devices comprise one or
more members of the list comprising: darts, balls, canisters and bombs.

13. The method of claim 8, wherein the valve is a hollow shell.

14. The method of claim 8, wherein one or more balls may be injected and
launched through the plug-valve.

15. The method of claim 8, wherein the plug-valve has a swept cutout
through at least 90 degrees of the valve's range of motion.

Description:

BACKGROUND OF THE INVENTION

[0001]The statements in this section merely provide background information
related to the present disclosure and may not constitute prior art.

[0002]The present invention is related in general to equipment for
servicing subterranean wells. Particularly, the invention relates to a
cementing head that is intended to drop a combination of darts, balls,
bombs and canisters in order to activate downhole equipment, launch
cementing plugs, deliver chemical products, or the like.

[0003]Tools currently available on the market for downhole services
implement a modular design with darts that are preloaded in baskets
within the modules. The modules are connected to one another using
clamps. The darts are held in place mechanically and released by removing
the mechanical obstruction and redirecting the flow of the pumped fluid
(hereinafter called "process fluid") through the dart basket. The darts
are then pumped through the tool by the fluid. The first dart to be
launched is placed in the lowest module, with subsequent darts passing
through the baskets vacated by the earlier darts.

[0004]Darts in prior designs are launched by blocking the bypass flow of
the process fluid and forcing the fluid through the dart chamber. The
dart forms an initial seal when placed into the basket. When fluid enters
the dart chamber, pressure builds and breaks the seal, forcing the dart
out of the basket, through the tool and into the main process-fluid
stream.

[0005]Some prior art designs consist of modules such as those described in
U.S. Pat. Nos. 4,624,312 and 5,890,537. The darts are loaded from the
topmost module, through the swivel if necessary, and pushed down to their
respective baskets with a long rod. The modules have valves that are used
to select between the dart and the bypass flow. The valve itself serves
as the mechanical obstruction that prevents the dart from prematurely
launching. When the valve is turned, it simultaneously opens a passage
for the dart while closing the passage of the bypass flow.

[0006]Another portion of the module is used to launch balls that flow down
the well and seat within plugs. Once seated, the balls block the flow of
process fluid through the plug, and the resulting pumping-pressure
increase causes shear pins to rupture, releasing the plug from its seat.
The ball launching portion of the module adds significant length to the
cement head.

[0009]In a first aspect, the present invention relates to a multiple
activation-device launching system for a cementing head having a launcher
body comprising a plug valve through which a process fluid and activation
devices may pass, and through which balls may be launched when the plug
valve is in either the main-flow or bypass-flow position.

[0010]In another aspect, the present invention aims at a plug-valve system
for a cementing head that allows the deployment of balls into the
process-fluid stream when the valve is in either the main-flow or
bypass-flow position. In the main-flow position, balls may pass through
the valve in the same manner as other activation devices, including
darts, canisters and bombs. In the bypass-flow position, balls may be
inserted through a passage inside the valve axle. An advantage of the
dual functionality of this design is the reduction of the length of the
cement-head assembly.

[0011]To allow ball deployment in either the main-flow or bypass-flow
position, the valve preferably has a swept cutout through at least 90
degrees of the valve's range of motion. In addition, the valve may be
fabricated as a hollow shell.

[0012]The activation devices may also contain chemical substances that,
upon exiting the launching chamber, are released into the well.

[0013]In yet another aspect, the present invention pertains to a method
for deploying one or more activation devices into a process-fluid system,
utilizing a multiple-activation device launching system for a cementing
head comprising a plug-valve that allows the deployment of balls into the
process-fluid stream when the valve is in either the main-flow or
bypass-flow position.

[0014]In a preferred embodiment, the method comprises pumping a process
fluid through the main-flow portion of the launcher body, placing the
plug valve in the main-flow position and, if desired, allowing one or
more activation devices to pass. The plug valve may then be placed in the
bypass-flow position, opening a passageway inside the plug-valve axle
through which balls may be inserted into the process-fluid stream. After
launching one or more balls, the plug-valve may be set back to the
main-flow position, allowing the passage of additional activation
devices. This operating sequence may be repeated until a sufficient
number of activation devices have been deployed to complete the
treatment.

[0015]The method may further comprise the use of activation devices that
contain a chemical substance. The chemical substance is here released
into the well after exiting the launching chamber.

[0016]Although the disclosed plug-valve system is mainly being presented
in the context of well cementing, it will be appreciated that the
process-fluid stream could comprise other well fluids including, but not
limited to, drilling fluids, cement slurries, spacer fluids, chemical
washes, acidizing fluids, gravel-packing fluids and scale-removal fluids.

[0018]FIG. 2 is a conceptual view of a cementing head plug valve system
that allows the release of darts when in the main-flow position, and also
allows the release of balls in either the main-flow or bypassflow
position. In this figure the valve is shown in the bypass-flow position.

[0019]FIG. 3 depicts the ball launching process, whereby a ball is being
injected into the well by passing though the axle of the plug valve
system.

[0020]FIG. 4 shows the ball flowing down toward the wellbore after
launching.

[0021]FIG. 5 depicts the dart launching process, whereby the plug valve is
rotated into the main-flow position, removing the barrier that previously
prevented dart movement. This figure also shows that another ball may be
placed into the plug valve axle.

[0022]FIG. 6 shows the dart flowing down toward the wellbore after passing
through the valve

[0023]FIG. 7 shows a subsequent ball launching process, with the valve in
the main-flow position.

[0024]FIG. 8 shows the ball flowing down toward the wellbore after
launching.

DETAILED DESCRIPTION

[0025]When cementing the annular space between tubulars and the walls of a
subterranean wellbore, it is usually necessary to minimize or prevent the
commingling of the drilling fluid, spacer fluid and cement slurry.
Commingling may result in adverse rheological effects, dilution of the
cement slurry and compromised zonal isolation. One way to minimize
commingling involves using wiper plugs to separate fluids as they travel
down the tubulars. Wiper plugs also clean the inner surface of the
tubulars.

[0026]FIG. 1 depicts a conventional single-stage subsea plug launching
system. The cementing head 1, located above the rig floor 2, is made up
to the drillpipe 3, which serves as the casing landing string and
controls the cementing plug release. The head contains a launching ball 4
and dart 5. The subsea assembly 6, partially inside the casing to be
cemented 7, contains the top cementing plug 8 and the bottom cementing
plug 9. Both plugs are attached to the casing wall by shear pins.

[0027]Referring to FIG. 1, the casing 7 is initially filled with drilling
fluid or spacer fluid. Prior to pumping cement slurry, the bottom plug
launching ball 4 is released. The ball travels down the casing, seats
inside the bottom plug 9 and blocks fluid flow. The resulting pressure
increase causes the shear pins to rupture, releasing the bottom plug. The
bottom plug then travels down the casing and stops at the bottom. Extra
pump or hydrostatic pressure extrudes the ball through its orifice seat,
and cement displacement continues. A ball catcher 10 attached to the
lower end of the bottom plug retains the ball.

[0028]Once the cement slurry has been pumped, the top-plug launching dart
5 is released. It seats into the body of the top cementing plug 8.
Increased circulation pressure then causes the shear pins to rupture and
release the top plug. The cementing operation continues. At the end of
slurry displacement, the top plug stops above the bottom plug 9.

[0029]As depicted in FIG. 1, the ball-release mechanism 11 and the
dart-release mechanism 12 are preferably two separate components of the
cementing head. The resulting length of the cementing head can lead to
ergonomic and logistical problems, particularly in remote locations.
Therefore, there is an incentive to employ one release mechanism for both
darts and balls, thereby reducing the length of the apparatus.

[0030]According to a preferred embodiment shown in FIGS. 2-8, the
invention involves a plug valve 13 that controls the flow of process
fluid through the launcher body 14. The valve rotates around a hollow
valve axle 15, directing process-fluid flow through the bypass-flow path
16 (FIG. 2) or through the mainflow path 17 (FIG. 5). Flow is controlled
by adjusting the position of the bypass limiter 18 (FIG. 2). FIGS. 2-4
depict the valve in the bypass-flow position. The bypass-flow position
prevents movement of the dart 5 through the valve. Instead, at least one
launching ball 4 may pass through the hollow valve axle (FIG. 2), into
the fluid flow path (FIG. 3) and travel through the casing toward the
wiper plugs (FIG. 4).

[0031]When it is time to release the dart, the valve rotates to the
main-flow position, opening a pathway for the dart (FIG. 5) and allowing
it to pass through the valve and continue toward the wiper plugs (FIG.
6). During this period it is also possible to insert another ball inside
the valve axle for later release (FIGS. 6-8). Thus, balls may be launched
when the plug valve is in either position. The dual functionality of this
design reduces the length of the cement-head assembly.

[0032]To allow ball deployment in either the main-flow or bypass-flow
position, the valve has preferably a swept cutout through at least 90
degrees of the valve's range of motion. In addition, the valve may be
fabricated as a hollow shell, allowing a wider berth through which balls
may pass, and reducing the probability of their becoming stuck.

[0033]In addition to balls and darts, other activation devices such as
canisters and bombs may be released by this valve apparatus. The
activation devices may also contain chemical substances that, upon
exiting the launching chamber, are released into the well.

[0034]In a preferred embodiment, the present invention pertains to a
method of operating the plug-valve and launching activation devices which
comprises pumping process fluid through the main-flow portion of the
launcher body 14, placing the plug valve 13 in the bypass-flow position
and allowing at least one ball 4 to pass. The plug valve may then be
placed in the main-flow position, opening a passageway through which a
dart 5 or other activation device may be inserted into the process-fluid
stream. After the dart or other activation device has passed, additional
balls may be inserted as desired through the valve axle. The plug valve
may also be set back to the main-flow position, allowing the passage of
additional activation devices. This operating sequence may be repeated
until a sufficient number of activation devices have been deployed to
complete the treatment.

[0035]The method of operating the plug valve depicted in FIGS. 2-8 may
further comprise activation devices containing a chemical substance that
is released after the activation device exits the launching chamber. The
activation device may begin dispensing the chemical substance immediately
upon launching, or at any time thereafter.

[0036]In the method of operating the plug valve depicted in FIGS. 2-8, the
process fluid may comprise one or more fluids employed in well-service
operations. Such fluids include, but are not limited to, drilling fluids,
cement slurries, spacer fluids, chemical washes, acidizing fluids,
gravel-packing fluids, scale-removal fluids. In addition, the activation
devices may comprise darts, balls, bombs and canisters.

[0037]It will be appreciated that multiple-stage plug launching systems
are also envisioned in the present invention. In addition, the invention
is not limited to subsea plug launching systems.

[0038]The preceding description has been presented with reference to
presently preferred embodiments of the invention. Persons skilled in the
art and technology to which this invention pertains will appreciate that
alterations and changes in the described structures and methods of
operation can be practiced without meaningfully departing from the
principle, and scope of this invention. Accordingly, the foregoing
description should not be read as pertaining only to the precise
structures described and shown in the accompanying drawings, but rather
should be read as consistent with and as support for the following
claims, which are to have their fullest and fairest scope.